Anti-aliasing and Gamma Compression
Digital images are usually stored in a gamma-compressed format, but an optical anti-aliasing filter is linear. So to downsample an image in a way that would match optical blurring, one should first convert it to a linear format, then apply the anti-aliasing filter, and finally convert it back to a gamma compressed format. Computing anti-aliasing directly on the gamma-compressed image will lead to bright details (such as a cat's whiskers) becoming visually thinner, and dark details (such as tree branches) becoming thicker, relative to the optically anti-aliased image. Almost all image editing software, including Final Cut Pro, Adobe Photoshop and GIMP, process images in the gamma-compressed domain.
Read more about this topic: Spatial Anti-aliasing
Famous quotes containing the word compression:
“The triumphs of peace have been in some proximity to war. Whilst the hand was still familiar with the sword-hilt, whilst the habits of the camp were still visible in the port and complexion of the gentleman, his intellectual power culminated; the compression and tension of these stern conditions is a training for the finest and softest arts, and can rarely be compensated in tranquil times, except by some analogous vigor drawn from occupations as hardy as war.”
—Ralph Waldo Emerson (1803–1882)